The production of tires includes the step of placing an uncured tire within a mold at which time heat and pressure is applied to the uncured tire in order to change its state to a cured condition. During the curing process, the uncured tire is placed inside of a metal mold that surrounds the exterior of the uncured tire. An expandable rubber bladder is positioned inside of the uncured tire, when it is within the mold, and can be expanded in order to apply pressure to the inside surface of the uncured tire. Steam, hot water, or inert gas can be transferred into the expandable bladder in order to cause it to assume an expanded state. The pressure applied by the expandable bladder forces the uncured tire against the mold to cause the uncured tire to be under pressure forces. Heat may be simultaneously applied, and the combination of heat and pressure applied for a particular time effects the curing process. The cured tire may then be removed from the mold and transported downstream for subsequent processing.
The expandable bladder may be punctured, or can otherwise leak, thus causing the expandable bladder to exert less pressure on the uncured tire than originally intended. Since less pressure is being applied to the tire during the curing process, the tire may not be fully cured and must be scrapped. In production, it may be the case that six or seven tires are under cured through use of a damaged expandable bladder before the leak is caught resulting in all of these tires being scrapped. Tire production facilities automatically scrap a tire that is molded through the use of a leaking bladder.
One method of detecting a leaking bladder may be through visual inspection of the tire. Although effective, such method is time consuming, and due to a cooling circuit buffer between curing and inspection six or seven under cured tires will be produced that must be scrapped. Another method of detecting a leaking bladder is by the measurement of humidity. The amount of humidity detected over the ambient level at each press extraction can be measured and if a threshold level is sensed then it can be assumed the bladder is leaking. This method thus senses the amount of steam or moisture released from a leaking bladder. Although capable of sensing a leaking bladder, this technique is not considered industrially robust and sometimes may classify a non-leaking bladder as a leaking bladder.
Another way of determining whether the expandable bladder is leaking is by counting the number of steam, hot water, or inert gas injections during curing of the tire. If the number of pressure increases that are needed to keep the expandable bladder pressurized moves beyond a threshold number it can be determined that the expandable bladder is leaking. Although capable of catching large leaks of the expandable bladder, this method may not be capable of detecting smaller leaks of the expandable bladder and thus is not dependable. Although mechanisms of detection of bladder leakage exist, none of them allow for the detection of a bladder leak that results in reliable detection of an expandable bladder leak with minimum tire scrap. As such, there remains room for variation and improvement within the art.
Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the invention.